<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<title>定位</title>
	<style type="text/css">
		.left{
			float: left;
		}
		.right{
			float: right;
		}
		.box{
			width: 200px;
			height: 200px;
			background: red url() 0 0 no-repeat;
			margin: 20px;
			color: #fff;
			font-size: 40px;
		}
		.box1{
			
			/*margin-top: 100px;*/
			background: blue url() 0 0 no-repeat;
		}
		.left .box1{
			position: relative;
			top:100px;
			left: 10px;
			z-index: -100;
		}
		.box2{
			/*margin-top: 100px;*/
		}
	</style>
</head>
<body>
	<div class="left">
		<div class="box box1">
		11

		</div>
		<div class="box">
			12
			
		</div>
	</div>
	<div class="right">
		<div class="box box1">
		21

		</div>
		<div class="box">
			22
			
		</div>
	</div>
</body>
</body>
</html>